#ifndef NORMAL_H
#define NORMAL_H

#include <cmath>
#include <random>
#include "../random/RandomGenerator.h"
#include "../../Assertions.h"

namespace Distribution {

	/** normal distribution */
	template <typename T> class Normal {

	private:

		const T mu;
		const T sigma;
		const T _a;

        Random::RandomGenerator gen;
		std::normal_distribution<T> dist;

	public:

		/** ctor */
		Normal(const T mu, const T sigma) :
			mu(mu), sigma(sigma), _a(1.0 / (sigma * std::sqrt(2.0 * M_PI))), gen(RANDOM_SEED), dist(mu,sigma) {

		}

		/** get probability for the given value */
		T getProbability(const T val) const {
			const T b = -0.5 * ((val-mu)/sigma) * ((val-mu)/sigma);
			return _a * std::exp(b);
		}

		/** get a normally distributed random number */
		T draw() {
			return dist(gen);
		}

		/** set the seed to use */
		void setSeed(const long seed) {
			gen.seed(seed);
		}

        /** get the mean value */
        const T getMu() {
            return this->mu;
        }

        /** get the standard deviation */
        const T getSigma() {
            return this->sigma;
        }

		/** get the probability for the given value */
		static T getProbability(const T mu, const T sigma, const T val) {
			Assert::isTrue(sigma > 0, "sigma must be >= 0");
			const T a = 1.0 / (sigma * std::sqrt(2.0 * M_PI));
			const T b = -0.5 * ((val-mu)/sigma) * ((val-mu)/sigma);
			return a * std::exp(b);
		}

	};

}

#endif // NORMAL_H